Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.64 (proteinase K)
 4,071 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Biotransformation of inorganic arsenic to form both methylarsinic acid (MA) and dimethylarsinic acid (DMA) has traditionally been considered as a mechanism to facilitate the detoxification and excretion of arsenic. However, the methylation of inorganic arsenic as a detoxification mechanism has been questioned due to recent studies revealing an important role of organic arsenic in the induction of genetic damage. In a previous report a reduction of DNA migration after treatment of cells with DMA was described. In order to further evaluate the possible induction of protein-DNA adducts, an experiment was performed taking into account other parameters and modifications of the standard alkaline comet assay. In addition, the results obtained with the comet assay were compared with those obtained by analyzing the induction of sister chromatid exchanges (SCEs). SCE frequencies were significantly increased in treated cells in relation to controls (p<0.001). Furthermore, in the standard alkaline comet assay, as well as in the control assay for proteinase K treatment, a significant dose-dependent reduction in tail moment was observed. Nevertheless, the post-treatment with proteinase K induced the release of proteins joined to the DNA and consequently, a dose-dependent increment in DNA migration was observed (p<0.001). These results suggest that DNA-protein cross-links may be an important genotoxic effect induced by dimethylarsinic acid in human MRC-5 cells.
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PMID:DNA-protein cross-links and sister chromatid exchanges induced by dimethylarsinic acid in human fibroblasts cells. 1572 7

Parasporal inclusion proteins produced by Bacillus thuringiensis strain A1470 exhibit strong cytotoxicity against human leukemic T cells when activated by protease treatment. One of the cytotoxic proteins was separated by anion exchange chromatography and gel filtration chromatography and designated Cry45Aa. Its gene was then expressed in recombinant Escherichia coli, in which the Cry45Aa precursor was accumulated in an inclusion body. It was solubilized in sodium carbonate buffer and processed with proteinase K, and cytotoxic activities of the protein against various mammalian cell lines were evaluated using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide assay. The protein exhibited high cytotoxic activity against CACO-2, Sawano, MOLT-4, TCS, and HL60 cells and moderate activity against U-937 DE-4, PC12, and HepG2 cells. On the other hand, the EC50 values against Jurkat, K562, HeLa, A549, Vero, COS-7, NIH3T3, CHO, and four normal tissue cells (human primary hepatocyte cells, UtSMC, MRC-5, and normal T cells) were >2 microg/mL.
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PMID:Identification of a novel cytotoxic protein, Cry45Aa, from Bacillus thuringiensis A1470 and its selective cytotoxic activity against various mammalian cell lines. 1607 12

Based on in vitro studies, several modes of action for arsenic have been suggested, although the mechanisms responsible for arsenic carcinogenesis have not been well established. In our previous study a dose-dependent increment in DNA migration was detected at low doses of sodium arsenite, but at higher dose levels a reduction in the migration was observed, suggesting the induction of DNA adducts. In order to confirm this hypothesis we performed the experiments considering other parameters and modifications of the standard alkaline comet assay. Additionally, the induction of sister chromatid exchanges was evaluated. The present study showed the induction by sodium arsenite of single strand breaks and DNA-protein adducts assessed by comet assay as well as of sister chromatid exchanges in the human lung fibroblast cell line MRC-5. The standard alkaline comet assay also revealed, at the highest arsenic concentration tested, a reduction in all the considered parameters in relation to untreated cells and the other doses. On the other hand, the incubation with proteinase K induced a dose-dependent increment in DNA migration as a consequence of the release of proteins joined to the DNA. Thus, sodium arsenite was able to induce both DNA-strand breaks and protein-DNA adducts in arsenic exposed MRC-5 cells, depending on the concentrations of arsenic salts tested.
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PMID:Induction of DNA strand breaks, DNA-protein crosslinks and sister chromatid exchanges by arsenite in a human lung cell line. 1614 91